51243021 has 6 divisors (see below), whose sum is σ = 74017710. Its totient is φ = 34162008.

The previous prime is 51243013. The next prime is 51243041. The reversal of 51243021 is 12034215.

It can be written as a sum of positive squares in only one way, i.e., 44555625 + 6687396 = 6675^2 + 2586^2 .

It is not a de Polignac number, because 51243021 - 2³ = 51243013 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 51242985 and 51243003.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51243001) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 2846826 + ... + 2846843.

It is an arithmetic number, because the mean of its divisors is an integer number (12336285).

Almost surely, 2^51243021 is an apocalyptic number.

It is an amenable number.

51243021 is a deficient number, since it is larger than the sum of its proper divisors (22774689).

51243021 is a wasteful number, since it uses less digits than its factorization.

51243021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5693675 (or 5693672 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 18.

The square root of 51243021 is about 7158.4230805395. The cubic root of 51243021 is about 371.4310805903.

Adding to 51243021 its reverse (12034215), we get a palindrome (63277236).

The spelling of 51243021 in words is "fifty-one million, two hundred forty-three thousand, twenty-one".